Field of the Invention
This invention relates to a coupler for air piping and electrical wiring in a truck, a trailer, etc., and more particularly to a coupler having air conduits of two systems, i.e., pneumatic pressure supply system and control system thereof.
A known coupler of this type has a construction as illustrated in FIGS. 1 to 4. In the figures, 1 is a female coupling member constituting a mate of the couple. This female coupling member 1 includes a cover 2 formed generally in a cup-shape and has, at an upper portion thereof, a mating face with a male half 15 of the couple. The female member 1 further has, at an upper peripheral portion, hooks 3 extending inwardly for engaging with the male member 15 when mated therewith. The female member 1 is connected, at side portions thereof, to an electric cable 4 and two valves 5 and 6 for two air conduits, respectively. The first valve 5 is for pneumatic pressure supply and the second valve 6 is for control of pneumatic pressure.
A plurality of terminal nuts 7 are provided in the female member 1 for connection of conductors extending from the electric cable 4. A tip end of each of the terminal nuts 7 projects above the mating face of the female member 1 to provide a connecting terminal 8 for a corresponding terminal 8' of the male member 15.
The female member 1 has two air conduits 9 and 10 communicating with the valves 5 and 6, respectively. The first air conduit 9 is dog-legged and extends from the side of the female member 1 to the central portion thereof. An o-ring 11 for airtight seal is provided on the inner face of a sidewall of an opening for the first air conduit 9. At the outside of the opening of the first air conduit 9, an annular groove 12 is formed concentrically with the opening. The third air conduit 10 is formed in dogleg which extends from the side of the female member 1 and opens at a bottom portion of the groove 12. Inner and outer sidewalls 17 and 18 of the groove 12 have o-rings 13 and 14 for airtight sealing, respectively.
On the other hand, the male coupling member 15 is formed smaller than the female member 1 so as to be fitted in the female member 1. The male member 15 is also connected to an electric cable 4' and valves 5' and 6' for air conduits 9' and 10', respectively. In the figures, parts or portions of the male member corresponding to those of the female member are designated by similar numerals with apostrophe.
The male member 15 has, at peripheral portions thereof, projections 3' extending outwardly for engagement with the hooks 3 of the female member 1. To engage the projections 3' with the corresponding hooks 3, the male member 15 is first fitted into the female member 1 and the male member 15 is rotated by a given angle (from a position shown by phantom line to a position shown by solid line) so as to bring the projections 3' under the hooks 3 and bring them into engagement with the respective hooks 3.
Each of connecting terminal 8' of the male coupling member 15 for electric wiring is formed in a clip-shape so as to hold the connecting terminal 8 of the female coupling member 1 therein. The connecting terminal 8' has ends opened outwardly for facilitating receiving of the corresponding connecting terminal 8 of the female coupling.
The male coupling member 15 has a mating face at a lower portion thereof. As in the female coupling 1, an opening of the second air conduit 9' and an annular groove 12' are formed on the mating face. The opening of the second air conduit 9' is defined by a sidewall 16' projected from the mating face of the male coupling member 15 and the sidewall 16' is fitted in the opening of the first air conduit of the female coupling member 1 to couple the air conduits 9 and 9' of the respective coupling members 1 and 15. In this case, hermetic sealing of the respective air conduits is attained by the o-ring 11. An inner wall 17' and an outer wall 18' of the annular groove 12' of the male coupling member 15 are formed so as to extend from the mating face of the male coupling member 15, and the inner wall 17' and the outer wall 18' are fitted in the groove 12 so that an annular air path is formed by the mating faces of the coupling members 1 and 15. Since the third and the fourth air conduits 10, 10' open at the grooves 12, 12', respectively, the third and the fourth air conduits 10, 10' are connected to each other through the annular air path. In this case, the sealing between the sidewalls of the groove 12 of the female member 1 and the inner and the outer wall of the groove 12' of the male coupling member 12' is attained by two o-rings 13, 14, respectively.
In the conventional coupler as described above, three o-rings 11, 13, 14 are used to prevent air leakage from two systems of the air conduits 9, 10 and resultant mixing thereof. However, as the number of the o-rings increases, more space is required for providing the rings and the diameter of the coupler becomes larger. In addition, the number of recesses for accommodating the o-rings therein is also increased, which makes the structure of the entire coupler complicated.